Tissue products such as paper towels, facial tissues, bath tissues, are often designed to have a soft feel. Softness is typically increased by decreasing or reducing bonding between fibers within the tissue product. While potentially improving softness, inhibiting or reducing inter-fiber bonding may adversely affect other important properties, such as the strength of the tissue product.
In other instances, softness may be enhanced by the topical addition of a softening agent to the tissue product. The softening agent may comprise, for instance, a silicone chemistry and may be topically applied to the tissue product by printing, coating or spraying. Although softening agents, such as silicone chemistries, make the tissue product feel softer, the agents can be relatively expensive, reduce absorbent rate and capacity, and may adversely affect the strength of the product.
In other instances softness may be enhanced by creping the tissue web. For example, U.S. Pat. No. 7,785,443 discloses creping a tissue web using a non-fibrous alpha-olefin polymer. The non-fibrous alpha-olefin polymer forms a thin film onto the tissue web, a portion of which remains on the surface of the web after it is creped from the dryer surface. While creping the tissue web in this manner improves softness, the water insoluble nature of the non-fibrous alpha-olefin polymer presents challenges to tissue machine operation. Further, to achieve the desired softness levels the non-fibrous alpha-olefin polymer is generally applied to the dryer at significantly high add-on levels compared to conventional creping compositions. For example, the non-fibrous alpha-olefin polymer may be applied in excess of 100 mg of creping composition per square meter of Yankee dryer surface area compared to about 5 to about 15 mg/m2 (milligrams per square meter of dryer surface area) for conventional creping compositions. The high add-on levels exacerbate the processing difficulties and increase costs.
Thus, there remains a need for treatments which improve softness without negatively affecting other important tissue product properties, such as strength, and which are compatible with current tissue machine operation. There also remains a need for treatments which produce the desirable tissue product improvements without excessive chemical usage or increased processing complexity and costs.